1. Field of Invention
This invention relates to compositions for melting ice and snow at low temperatures and more particularly, for melting ice on driveways, sidewalks and the like. The invention also contemplates the method for making the composition.
2. Description of the Prior Art
De-icing compositions have long been known and have been used to melt ice on driveways, sidewalks and the like. Such compositions have included unrefined rock salt, which is impure sodium chloride, calcium chloride, aluminum chloride, magnesium chloride and other salt materials. There have been disadvantages with these materials. For example, the impurities in the rock salt leave an unsightly coating on a melted surface which when tracked indoors damages floors and carpeting. Both rock salt and calcium chloride can cause damage to vegetation, and calcium chloride is difficult to handle, being extremely hygroscopic.
U.S. Pat. No. RE. 32,477, which is assigned to a common assignee, discloses a composition for melting ice from driveways, sidewalks and the like which includes sodium and potassium chloride and urea. This composition is not as damaging as other de-icer materials in that it does not have as adverse an effect on vegetation and does not leave unsightly coatings due to the fact that less sodium containing material is used to obtain the desired result. However, this composition does not melt ice at as low a temperature as may be desired. Lower temperature melting can be achieved using calcium chloride. However, calcium chloride is extremely difficult to handle due to its water absorption qualities. Anhydrous calcium chloride can chemically burn skin.